Electrophotographic duplicator

ABSTRACT

An electrophotographic copying machine utilizes an endless belt having a conductive film and carrying a photosensitive surface thereon. The photosensitive surface comprises a thin evaporated film of a non-crystalloid selenium formed on at least a portion of the film and an organic semiconductor film deposited on the evaporated film. The endless belt also includes means for indicating exposure frames and the endless belt is positioned so that the photosensitive surface receives the image by a detector mechanism which senses the exposure frames. The apparatus also includes a movable frame which is detachably mounted to the copying machine for tensioning, aligning, and maintaining the belt flat.

Tanaka et al.

1 Mar. 12, 1974 1 ELECTROPHOTOGRAPHIC [)UPLICATOR [75] Inventors: SusumuTanaka; Yuji Enoguchi;

Masaya Ogawa, all of Osaka, Japan [73] Assignee: Minolta CameraKabushiki Kaisha, Osaka-shi, Japan [22] Filed: Sept. 24, 1971 [21] Appl.No.: 183,416

[30] Foreign Application Priority Data Sept. 28, 1970 Japan 45-85471[52] US. Cl 355/16, 355/14, 198/184 [51] Int. Cl G03g 15/00 [58] .Fieldof Search 355/3, 14, 16; 198/202, 198/184 [56] References Cited UNITEDSTATES PATENTS I 3,520,604 7/1970 Shelffo 355/16 3,435,693 4/1969 Wrightet al. 198/202 3,540,571 11/1970 Morse 198/202 3,533,692 10/1970Blanchette 355/16 3,620,614 11/1971 Gunto 355/3 3,606,532 9/1971 Shelffoet a1 355/16 OTHER PUBLICATIONS IBM Technical Disclosure. Bulletin,Author-Hider et a1., Title-An Elcctrographic Printer with Asynchronouslmage Belt," Vol. 9,'No. l 1, 4-67.

Primary Examiner-Joseph F. Peters, Jr. Assistant Examiner-Alan MathewsAttorney, Agent, or FirmWatson, Cole, Grindle &

Watson 7 I 57 ABSTRACT An electrophotographic copying machine utilizesan endless belt having a conductive film and carrying a photosensitivesurface thereon. The photosensitive surface comprises a thin evaporatedfilm of a noncrystalloid selenium formed on at least a portion of thefilm and an organic semiconductor film deposited on the evaporated film.The endless belt also includes means for indicating exposure frames andthe endless belt is positioned so that the photosensitive surfacercceives the image by a detector mechanism which senses the exposureframes. The apparatus also includes a movable frame which is detachablymounted to the copying machine for tensioning, aligning, and maintainingthe belt flat.

11 Claims, 9 Drawing Figures PAIENIED AR 1 2 I974 FIG. 2

PATENTEDMAR 12 1914 SHEEI28F3- FIG. 3

l nna 47 PAIENTED m 12 m4 srm 3 M3 FIG.7

TIP DE TECTION CKT B2 3rd CONT CKT A2 CKT A3 EXPOSURE ADJUSTING CKT CONTTIP DE-- TECTION CKT Bl l I Is? CONT CKT START ELECTROPHOTOGRAPHICDUPLICATOR BACKGROUND OF THE INVENTION The present invention relates toa practical copying machine serviceable to produce a copy of books orthe like, and more particularly, to an electrophotographic copyingmachine of the type in which an electrostatic latent image is formed ona photosensitive plate in response to a mirror image of an originalpicture image by applying the Carlson image producing process. Subsequently, thereafter a dielectric coated paper contacts thephotosensitive plate and the electrostatic latent image is transferredonto the dielectric coated paper by means of the so-called electrostatictransfer method.

The practical copying machine in the prior art has been represented by axerography type copying machine and an electrofax type copying machine.The former has been used because a plurality of copied sheets can berapidly obtained thereby and these copies consist of uncoated papers oflight weight, and therefore are easy to handle. However has thedisadvantage that good clarity of a picture can not be expected fromthese copies since the exposure of a picture image is carried out bymeans of an original picture projecting optical system which movesrelative to the angular velocity of and concurrently with aphotosensitive substance on the surface of a drum. Further, due to thephysical processes such as the cascade development, the transfer, andthe cleaning operation carried out directly on the photosensitivesubstance, the quality of the picture is degraded on account of thephotosensitive substance which is accordingly damaged and degenerated.Moreover; the outstandingly large size of the copying machine itselfcannot be avoided in relation to the image making process which must beaccomplished therein.

The latter type machine has been used because the copying machine itselfis of a small size owing to the simplified image making process, and thecopying speed of the first copy sheet is fast, as well as the quality ofthe obtained copy is superior to that of the former machine. However, ithas the great disadvantage in that due to the quality of thephotosensitive zinc oxide paper of the obtained copy, the treatment ofthe obtained copy is not so feasible as the instance of an uncoatedpaper.

As described above, even though these practical copying machines in theprior art have been widely used 'by making use of their respectiveadvantages, neither of them is completely satisfactory due to theaforementioned disadvantage.

The known TESI method is an image producing method by which anelectrostatic latent image formed on a photosensitive body istransferred onto a different dielectric coated paper and is thendeveloped, but there are a variety of modes involved therein. Forexample, a dielectric coated paper contacts a photosensitive substancehaving an electrostatic latent image formed thereon, and both bases ofthe dielectric coated paper and the photosensitive substance aregrounded. Then the dielectric coated paper is separated therefrom, andthe electrostatic latent image being accordingly transferred onto thedielectric coated paper. According to this method, no physical processto be affected on the photosensitive substance is required in order totransfer the electrostatic latent image on the photosensitive substance,and a copy consisting of a desirable dielectric coated paper can beeffected therefrom.

While, at present, no practical copying machine in which theaforementioned method was embodied has been developed. This fact dependson the conventional photosensitive substance according to which theintensity of a copy is too low to obtain clear copies, in a case of therepeated use of an identical photosensitive plate, on account of thepre-exposure effect, and which is never appropriate to practical usefrom the view point of the required high speed in the copying operation.

SUMMARY OF THE INVENTION The inventors of the present invention havedisclosed a photosensitive plate of which the structure and thephotosensitive mechanism are quite different from those of aphotosensitive substance or a photosensitive sheet for use in apractical copying machine in the prior art, and which has greatmechanical strength and flexibility, and is capable of being charged toa high potential of 1,000V or higher. Also the photosensitive plate alsois highly sensitive to such a degree that the exposure of a pictureimage can be carried out solely with several lux-sec and with thepre-exposure effect reduced to an outstandingly small value.Additionally it is further capable of forming an electrostatic latentimage of high contrast and high resolving power. The inventors have alsodisclosed a transfer sheet onto which an electrostatic latent imageformed on the photosensitive plate can be efficiently transferred bymeans of the most simplified TESI method as described above.

It is an object of the present invention to provide a practicalelectrophotographic copying machine of the electrostatic latent imagetransfer type which uses the aforesaid photosensitive plate and transfersheet.

It is another object of the present invention to provide anelectrophotographic copying machine of the electrostatic latent imagetransfer type, in which an electrostatic latent image consisting of amirror image of a picture image is formed on a photosensitive platedisposed on an endless belt, and the electrostatic latent image istransferred onto a transfer sheet.

It is still another object of the present invention to provide anelectronic photograph copying machine which is endowed with highsensitivity and high resolving power so that the electrostatic latentimage therein can be easily transferred.

The other objects and advantages of the present invention will becomeapparent through the description of an embodiment thereof as set forthbelow.

The present invention is characterized by the following features whichare required to attain the various objects of the present invention asdescribed above.

One feature of the present invention resides in that an original sheetexposure station is mounted to the top of a copying machine, and anexposure optical system which projects the overall mirror image of apicture image is disposed under the rest exposure station. An endlessbelt conveying device which includes such structure as a belt zigzagpreventer, a belt tensioner and a belt flattener at the projectinglocation. Also a photosensitive plate is adhered to the endless belt soas to provide an original picture projection part. The result is thecapability of a picture image copy having outstandingly high quality ascompared with that of the drum type sequential exposure process of theprior art.

Another feature of this invention resides in that the photosensitiveplate disposed on the endless belt is the same size as an originalpicture to be projected thereon, and either one sheet or plural sheetsthereof are arranged thereon so that the photosensitive plate iseffectively made use of.

Still another feature of this invention resides in that arranged aroundthe endless belt conveying device are a corona discharge device, anelectrostatic image transfer conductive roller and a photosensitiveplate location detecting device, and the photosensitive plate is set upin such a manner that it is usually kept stationary at the location ofthe linear plane portion of the endless belt, and is conveyed during acopying operation. Then it is stopped at the initial location just whenthe final copying operation is completed, the mechanical degeneration ofthe photosensitive plate being accordingly prevented.

Further another feature of this invention resides in that a controlcircuit is provided in order to programmably control the drive and stopactions for the endless belt conveying device, as well as all operationssuch as the ON-OFF action for the corona discharge device, the ON-OF Faction for the illuminating light source of the original sheet exposurestation, and the ON-OFF action for the transfer sheet supplying device.Thereby any useless conveyance of the photosensitive plate and anywasteful consumption of power are obviated, in addition, a speedycopying operation is accordingly made possible.

Another specific feature of this invention resides in that the endlessbelt conveying device is removably mounted to the machine body, and abelt zigzag preventing roller f the endless belt device is pressedagainst a belt tensioner device so as to enable the endless belt to beeasily replaced.

Still another specific feature of this invention resides in that a thinevaporated aluminum film is provided on the endless belt as anelectrode. Also arranged thereon is a flexible photosensitive platecomposed of successive laminations of a thin evaporated film of anoncrystalloid selenium, either an organic semiconductor paint film or athin evaporated film ofa non-crystalloid selenium, a thin evaporatedfilm of a Se-Te alloy, and an organic semiconductor paint film. Thetransfer sheet is such that a thin film of a high dielectric substanceis coated on a paper base which has been given a conductive treatment.Copies thereby obtained are better and clearer than those obtainable bymeans of a practical copying machine in the prior art, in addition, aspeedy copying operation being accordingly made possible.

BRIEF DESCRIPTION OF THE DRAWING FIGS. 1A 1C are illustrative viewsshowing respectively the structure of a photosensitive plate and atransfer sheet which are adoptable to a copying machine in accordancewith the present invention.

FIG. 2 is a perspective view showing the outside appearance of a copyingmachine in accordance with the present invention.

FIG. 3 is a sectional elevation view showing an essential part of thecopying machine.

FIG. 4 is a perspective view showing an endless belt of the copyingmachine, wherein a part of the endless belt is cut away.

FIG. 5 is a perspective view showing an essential part of the endlessbelt.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photosensitive plate P foruse in the present invention is, as shown by FIG. IA, composed of aflexible film base a consisting of a polyester film with a thickness ofp, a thin aluminium film b evaporated on base a to serve as anelectrode, a very thin noncrystalloid selenium evaporated film claminated on aluminium film b, and an organic semiconductor paint film dcoated on selenium film c. The semiconductor paint consisting of apolyvinyl carbazole (PVK), a diphenyl trichloride (flexibility agent)and a monochlorobenzene (solvent). The PVK film d of the uppermost layerholds electric charges, and the thin selenium film 0 is for absorbinglight rays and generating electric charge carriers. The thin aluminiumfilm b forms a high rectifying barrier at the boundary interface withthe selenium film c and completely checks positive holes from pouringinto the thin selenium layer 0. When the surface of the photosensitiveplate is negatively charged and exposed to light rays, the positiveholes generated in the thin selenium film c migrate to the PVK film d,and are shifted towards the surface thereof. The electric charge at thesurface is neutralized so as to form an electrostatic latent imagethereon. The above construction is a particular photosensitive platewhich has been improved intensity and contrast characteristics of thepicture image.

Next, if the photosensitive plate is modified, as shown by FIG. 1B, insuch a manner that a thin evaporated film e of a Se-Te alloy isinterposed as an intermediate film between the PVK film d and the thinselenium film 0, the sensitivity of the photosensitive plate P isgreatly increased because the thin selenium film c will no more longerabsorb light rays and merely checks positive holes against theirmigration thereinto by forming a high rectifying barrier at the boundaryinterface with the aluminium evaporated film b. It is possible to mixtellurium in a weight ratio ranging from 10 percent up to 60 percentinto the selenium so as to make up the Se TeZillbyfiTffi w Moreover,since photosensitive plates P are respectively so constructed that theselenium film c and the Se-Te alloy film e are so thineach thickness isless than l J. -the PVK film d is made of a macromolecular substance,and the aluminum film b and the selenium evaporated film c are solidlyadhered to each other in such a way that the aluminium film is firstexposed to the glow discharge and forcibly oxidized by ionbombardment.Selenium is evaporated thereon in a vacuum so as to obtain a strongcohesion therebetween, and when the photosensitive plate is shaped, forexample, into an endless belt, even if it is stretched between tworollers of 30 m 42 and continuously rotated at the high speed of I m/secfor a period of 1,000 hours, the aluminium film does not separate fromthe selenium film, and accordingly it can be reliably put to practicaluse as a belt-like photosensitive plate.

The photosensitive plate P is charged and an electrostatic image isformed thereon by an exposure of a picture image. Subsequently atransfer sheet T, as shown by FIG. 1C is contacted therewith which iscomposed of a paper 3 of a thickness from 25 ,u. to 150 ,u.. Thecombined plate and transfer are given a conductive treatment, and adielectric resin film h coated on the paper g by painting to a drythickness from 2 t up to ,u.. The resin may comprise any resin of highdielectric strength such as, for instance, polyethylene, wax, alkydresin, cellulose acetate, epoxide, and vinyl chloride acetate copolymer.The attached transfer sheet T is then pressed from its rear side bymeans of a roller which has been grounded and thereafter it is developedin a liquid. The result is a copy which is better than that obtainableby a practical copying machine in the prior art, particularly, if thephotosensitive plate of the construction shown in FIG. 1B is used. Itwas confirmed that when it was charged to a potential higher than1,000V, and exposed to a picture image of several luxsec, then obtainedon the transfer sheet T was a very clear visible image with nobackground contaminated and having high contrast and high resolvingpower (more than 50 lines/mm).

FIG. 2 and FIG. 3 are schematic views showing the overall constructionof the copying machine in accordance with the present invention,wherein, on the top of a housing 1 of the copying machine, a glass plate2 for use as a photographing station is fixed. Arranged under both sidesof the photographing glass plate 2 are light sources 5 affixed withreflection shades 4 which illuminate the photographing surface of anoriginal picture 3 which is positioned on the glass plate 2. Lightsources 5 being, for example, an iodine lamp or a xenon lamp with a formapproximate to a tubular light source. The light rays incident upon thesurface of the original picture 3 are introduced to a mirror imageprojecting optical system which comprises a first planar mirror 6 forreflecting the light, a set of projection lenses 7, and a second planarmirror 8. The optical system is arranged underneath the glass plate 2 asshown in FIG. 3. Projection lenses 7 comprising either one lens orplural lenses, or else a zoom lens, and being arranged in such a waythat the enlargement, the equality and the reduction of an image size isthereby made possible as desired. But such an arrangement is not shownin the drawing, as it is a well known means. A photosensitive plate P onwhich a mirror image of the original picture 3 being focused by means ofthe projecting optical system is mounted onto an endless belt 10 whichis conveyed by an endless belt conveying system 9, and only one plate Pis shown in the drawing, but it may be moditied to a number of plates.

The detailed construction of the endless belt conveying device 9 will behereinbelow described with reference to FIG. 4. Both side plates 11 and12 composing the main body of the endless belt conveying device 9 aresolidly built up by means of both side plate connecting members 13 and14, and a plate 15 is disposed so as to occupy the area corresponding tothe projected location between the top levels of both side plates 11 and12 in order to keep endless belt 10 flat. Moreover rollers 16 and 17 arerotatably mounted to both side plates 11 and 12 on the fore and aftsides of the flatness keeper plate 15 in order to keep the endless belt10 in a plane. Members 15 through 17 constituting a belt flatnesskeeping device.

Furthermore, on a bearing holding member 18 rigidly fixed to the sideplate connecting member 13, two bearings 20 and 21 which hold a shaft 19are mounted,

and fixed on one end of the shaft 19 is the main part of a metal fitting24 of which side flanges 23 rotatably support a roller 22 for preventingany possible zigzag of the endless belt 10. Formed on the side flanges23 are protrusions 23' which prevent the belt 10 from projecting axiallyoutwards of the roller 22 due to any zigzag tendency. Assuming now thatthe belt 10 is dislocated towards the side plate 12, the side edge 10'of the belt 10 comes into contact with the protrusion 23', thereby themetal fitting 24 is clockwise rotated about the shaft 19 so as to raiseup that side with respect to the shaft 19. The lateral tensional mode ofthe belt 10 is accordingly varied, the belt 10 is therefore shiftedtowards the side plate 11 so that it. is automatically returned to itsinitial situation, as well as the metal fitting is also returnedconcurrently to its initial status.

Also provided is a belt tensioning device which comprises a collar 25disposed between bearings 20 and 21 of the shaft 19 and fixed to theshaft 19 by means of a stop screw. A compression spring 26 is interposedbetween the collar 25 and the bearing 21,and which tensions the belt 10by biasing the metal fitting 24 together with the roller 22 at all timesin the axially left direction of the shaft 19 on account of thecompression spring 26.

The belt zigzag preventing roller, flatness keeper rollers 16 and 17,and a belt driving roller 27 which is rotatably fitted to both sideplates 11 and 12 and drives the endless belt 10, are all covered by theendless belt 10.

An grounded conductive roller 28 is rotatably mounted on the main bodyof the copying machine so as to abut the belt drive roller 27 as shownin FIG. 3, and an electrostatic transfer station is composed of thesetwo rollers 27 and 28.

As shown in FIG. 4, a gear 29 which is fixed on one end axle of theroller 27 is arranged so as to mesh, at the time when the endless beltconveying device is placed into its operating location, with a gear 31which is driven by a sprocket wheel 30 which is rotatable only when itis engaged by an electromagnetic clutch CL so as to be interlocked withthe chain transmission from a motor Mm which is continuously running asa driving source provided in the main body of the copying machine.

In the case where the endless belt 10 is composed of a flexibledielectric substance, such as polyester film, namely, in the case wherethe flexible film base a in the photosensitive plate P of theconstruction shown by FIGS. 1A and 1B, the photosensitive plate P iscomposed of a conductive layer 32, as shown in FIG. 5, such as anevaporated aluminum layer, a carbon powder containing resin layer, a Cu]layer etc., which is made up around the periphery of both side edges ofthe endless belt. Roller 33 is rotatably fitted to a spindle rigidlyfixed to the main body of the copying machine, grounded and arranged soas to be always kept in contact with the conductive layer 32. Aluminumelectrode b of the photosensitive plate P shown in FIGS. 1A and 1B isalso grounded.

Whereas, in the case where the endless belt 10 itself is a conductivebelt, such as a stainless belt, a Ti belt etc., it is sufficient to usea roller 27 which has been made conductive and is grounded.

Arranged around the endless belt conveying device 9 and installed to themain body of the copying machine are, with the exception of theconductive transfer 36 and 37 are respectively as shown in FIG. 6. Adark chamber 38 is separated into two compartments, an illuminating lampL is disposed in one I compartment thereof, and a photoelectric elementCdS is disposed in the other compartment. The compartments beingrespectively provided with a small hole 38 through the bottom thereof,whereby a photosensitive plate tip detection mark 35 which has beeninscribed on a highly reflective member such as an evaporated aluminiumlayer is detected by the photoelectric element CdS by virtue of the lampL of which the light beam is reflected on the mark 35, and becomesincident upon the photoelectric element CdS so that the arrival of thephotosensitive plate P thereat can be determined. However, the topdetection for the photosensitive plate P may be carried out inaccordance with any other known means such as, for instance, to providethe belt with a small hole by which a micro switch is actuated, or elseto provide a cam which can be interlocked with the belt 10.

The photosensitive plate P on the endless belt 10 is operated in such amanner that it is usually kept stationary at the location detected bythe detecting device 36 as shown in FIG. 3. But during a copyingoperation it is conveyed until it arrives at the projecting locationwhere its movement is terminated on account of its being detected by theother detecting device 37. Upon completion of the exposure, it is againconveyed until it arrives at the initial location where its movement isstopped owing to the detecting device 36 which detects it again.

At a location above both rollers 27 and 28 composing the electrostaticimage transfer station, stacked on a rack 39 are a plurality of transfersheets T each of which is to be made up into a final copy, and which aresent out one by one sequentially by means of a feeding roller 40 drivenby a motor M It is understood that each sheet is transmitted inaccordance with a predetermined control determined by the movement ofthe belt 10. It is controlled so that both tips of the photosensitiveplate P on the belt 10 and the transfer sheet T are simultaneouslyconveyed into the clearance between both rollers 27 and 28.

Arranged beneath the transfer station are a pair of transmitting rollers44 and 45 for introducing the transfer sheet T into the clearancebetween a developing belt 42 and an electrode 43 which are both disposedin a liquid type developing apparatus 41. The developing apparatus beingconstructed in such a manner that a liquid type developer is circulatedby means of a pump 47 driven by a pump motor M (not shown in FIG. 3) sothat the developer sucked from a developer reservoir 46 is supplied tothe developing apparatus 41 through a supply pipe 48. Any excess of thedeveloper is returned to the reservoir 46 via a return pipe 49, andexcessive developer contained in transfer sheet T being squeezed bymeans ofa pair of squeezing rollers 50 and 51 arranged appropriately inthe developing apparatus 41. A conveyor belt 54 is disposed forconveying the transfer sheet from the developing apparatus 41 to a copyreceiving tray 53 which is fixed to the side plate 52 of the copyingmachine. Also disposed above the conveyor belt 54 is a dry fixing device57 consisting of a heater 55 and an air fan 56 driven by a fan motor Mnot shown in the drawing. The heater 55 is not necessarily required inthe case where a self fixing agent is contained in the developer. Inaddition, transmitting rollers 44 and 45, developing belt 42, squeezingrollers 50 and 51, and conveyor belt 54 are all interconnected with themotor M which is the driving source of the endless belt 10, by thetransmitting means of the sprocket wheel and the chain.

The copying machine of the present invention being constructed asdescribed above, the electric circuit thereof is connected as shown inFIG. 7. A main switch S a starting switch S and an exposure lightquantity regulating dial D are mounted at their respective locationswhere they are easily handled from the outside of the copying machine asshown in FIG. 2.

The operation of the copying machine in accordance with the presentinvention will now be described. The main switch S is first switched toON. The motor M the pump motor Mp and the fan motor M are therebydriven, and the heater 55 is simultaneously activated. The transmittingrollers 44 and 45, the developing belt 42, the squeezing rollers 50 and51, and the conveyor belt 54 are concurrently driven, but the endlessbelt 10 is not driven owing to the clutch having been disengaged. Theliquid type developer is continuously circulated by the pump motor Mpwhich is running.

After an original picture 3 is placed on the glass plate of thephotographing exposure station 2, if the starting switch S is pressed inorder to start a copying operation, thereby the first control circuit Ais actuated so that the clutch CL is operated so as to have the drivingforce of the motor M transmitted to the driving roller 27. The endlessbelt 10 is accordingly rotated to have the photosensitive plate Pconveyed, and a high voltage transformer HV shown in FIG. 7 issimultaneously activated so as to render a corona discharge device 34shown in FIG. 3 operable. Consequently, the photosensitive plate P is insequence charged so as to be made photosensitive as it is conveyed underthe corona discharge device 34. At the time when the photosensitiveplate P arrives at the projecting location, more particularly, at themoment when the top detection mark 35 is aligned with the photosensitiveplate tip detecting device 37, the tip detection circuit B is actuatedso as to render the second control circuit A operable. On account of theactivation of this control circuit A the high voltage transformer HV iscut off so as to have the operation of the corona discharge device 34terminated. Concurrently the current to the clutch CL is also shut offso that the rotation of the endless belt 10 is terminated, thephotosensitive plate P being thereby stopped at the projecting location.

Simultaneously, the light source 5 is actuated so as to illuminate theoriginal 3, thereby a mirror image of the original image is projected onthe photosensitive plate P via the planar mirror 6, the projection lens7 and the planar mirror 8, and an electrostatic image being accordinglyformed thereon.

Additionally, the control of the second control circuit A is carried outby means of the exposure light quantity adjusting dial D via an exposurelight quantity adjustment circuit C.

Upon completion of the operation due to the second control circuit A thethird control circuit A is actuated so that the light source 5 isextinguished, and the current to the clutch CL is in turn restored so asto have the endless belt again rotated. Simultaneously, the motor M isalso started so that another transfer sheet is taken out from the stackby means of the feeding roller 40.

The photosensitive plate P and the transfer sheet T are together caughtbetween both rollers 27 and 28 so as to contact closely with each other.The electrostatic image on the photosensitive plate P is transferred tothe transfer sheet T. The photosensitive plate P is conveyed after thecompletion of the transfer, and at the moment when the tip detectionmark 35 thereof is sensed by the detecting device 36, the tip detectioncircuit B is actuated so as to terminate the operation of the third control circuit A Consequently, the clutch CL is disengaged so as toterminate the rotation of the endless belt 10, and the photosensitiveplate P being thereby stopped at the initial location thereof.

Whereas, the transfer sheet T having the electrostatic image transferredthereon is immediately conveyed by means of the transmitting rollers 44and 45 to the liquid type development apparatus 41. The electrostaticimage is developed with a toner while the transfer sheet T is beingconveyed by the development belt 42 towards the squeezing rollers 50 and51 which squeeze off the excessive developer contained in the transfersheet T, which is thereafter conveyed on the revolving conveyor belt 54and dried thereon until it is sent out to be stacked in the receivingtray 53.

In addition, the control circuits aforementioned are respectivelycomposed of by making use of various known means such as, for example, atimer, a cam and a microswitch, a means being sequentially operated byvirtue of a relay and a microswitch, and the like.

The descriptions shown hereinbefore are all concerned solely with theoperation in the case where only one photosensitive plate P is disposedon the endless belt 10 and only one copy is produced therefrom. However,any predetermined number of copies can be continuously made up whenplural copies are demanded, if a known counter which is not shown in thedrawing is provided, and the first control circuit A is made operativeat each time when the detection mark 35 is detected by the detectingdevice 36 until the final transfer sheet is signaled by the counter, andthe endless belt 10 is continuously rotated until the predeterminednumber of copies are made.

Furthermore, if another photosensitive plate is additionally mounted onthe planar portion of the endless belt 10, so that plural photosensitiveplates are arranged thereon, the copying speed for the plural sheets isthereby made faster. Moreover, in the case where the photosensitiveplate P is flexible, wherein disposed on the endless belt 10 is a thinevaporated aluminium film, and sequentiallylaminated thereon are a thinevaporated non-crystalloid selenium film, a thin film layer consistingof either an organic semiconductor paint or an evaporatednon-crystalloid selenium, a thin evaporated Se-Te allow film, and anorganic semiconductor paint film, the photosensitive plate P is notalways required to stop at the original picture projecting locationbecause of its outstandingly high sensitivity. The formation of anelectrostatic image can be successfully carried out by means of a mereinstantaneous projection thereof with a flash bulb such as a xenon lampor the like. Moreover, if the second control circuit A is not endowedwith the function to cut ofi the current flowing to the clutch CL, thecontinuous copying operation can be accomplished at an increased highspeed.

Furthermore, in the copying machine according to the present invention,the endless belt conveying device 9 can be easily taken out of thecopying machine by disengaging its gear 29 from the gear 31. The endlessbelt 10 is also capable of being taken out by inwardly pushing thezigzag preventing roller 22 against the bias of the compression spring26. Accordingly, the replacement of the photosensitive plate P can beeasily accomplished.

Since the copying machine according to the present invention is asdescribed above, a picture image of an outstandingly high quality can beproduced, as compared with that in accordance with a conventionalcopying machine, for example, a transfer type copying machine such as asequential exposure system provided on a drum with a photosensitivesubstance. Any change of the magnification such as the reduction or theenlargement thereof can be very simply put in practice, also on accountof no drum being required therein. There exists only a small dead spaceso that there is provided a transfer type copying machine of a compactconformation size which could not be heretofore realized. Further, thereare obtained copies that are light and easy to handle, since they arecomprised of dielectric coated sheets of high quality owing to the superfine grains particular to the liquid type development. Additionally,because the photosensitive plate P is disposed on the flat portion ofthe endless belt 10, and it is located at the flat portion at all timeswhen the belt is stationary, the photosensitive plate is not impaired byany mechanical permanent strain so that it can be effectively put touse. Moreover, the copying machine is capable of rapidly producing aplurality of copies by means of the program control, and each of thecopies obtained by said copying machine provided on the endless beltthereof with a flexible photosensitive plate composed of a thinevaporated aluminum film, and thin film layers which are furtherlaminated in sequence thereon, and which comprise an evaporatednoncrystalloid selenium film, a film of either an organic semiconductorpaint or an evaporated non-crystalloid selenium, an evaporated Se-Tealloy film, and an organic semiconductor paint film, is better andclearer than the same obtained by any conventional practical copyingmachine as well as it becomes possible to make a multitude of copies ata higher speed than ever before. In addition, the photosensitive platecan be replaced merely by replacing the endless belt only, and thereplacement can be very simply and easily carried out. As describedhereinabove, the present invention is outstandingly effective in that itis capable of providing an ideally practical copying machine which isendowed with the advantages of the individual copying machines in theprior art, and from which the disadvantages thereof have beeneliminated.

What is claimed is:

1. An electrophotographic copying machine, comprising:

an exposure station for supporting an original document to be exposed;

an optical system for projecting a mirror image of said originaldocument;

means for conveying a photosensitive surface to receive the projectedimage, and including an endless belt having a conductive film thereonand supporting said photosensitive surface, said photosensitive surfacecomprising a thin evaporated film of noncrystalloid selenium formed onat least a portion of said conductive film, and an organic semiconductorfilm deposited on said evaporated film;

means for driving said endless belt;

a movable frame for tensioning and aligning said endless belt;

said endless belt including means for indicating exposure frames;

means for detecting said exposure frames;

means responsive to said detecting means for controlling said drivingmeans to position said photosensitive surface to receive said image;

means for supplying transfer sheets;

means for contacting individual ones of said transfer sheets with saidphotosensitive surface; and

means for developing and fixing the image on said transfer sheets.

2. An electrophotographic copying machine as in claim 1 wherein saidthin evaporated film is a seleniumtellurium alloy.

3. An electrophotographic copying machine, comprising:

an exposure station for supporting an original document to be exposed;

an optical system for projecting a mirror image of said originaldocument;

means for conveying a photosensitive surface to receive the projectedimage and including an endless belt supporting said photosensitive.surface;

means for driving said endless belt;

frame means for maintaining the longitudinal alignment of said endlessbelt while being driven including a movable frame supported on a shaftextending along the longitudinal axis of said endless belt, said movableframe including a pair of said frames between which an idling roller isrotatably mounted and over which said endless belt travels, said sideframes each having a protrusion extending outwardly of said idlingroller so that should said endless belt shift toward either of said sideframes, the edges of said belt will come into contact with one of saidprotrusions thereby causing said movable frame to rotate about saidshaft to realign said belt;

saidendless belt including means for indicating exposure frames;

means for detecting said exposure frames;

means responsive to said detecting means for controlling said drivingmeans -to position said photosensitive surface to receive said image;

means for supplying transfer sheets;

means for contacting individual ones of said transfer sheets with saidphotosensitive surface; and

means for developing and fixing the image on said transfer sheets.

4. An electrophotographic copying machine, comprising:

an exposure station for supporting an original document to be exposed;

an optical system for projecting a mirror image of said originaldocument;

means for conveying a photosensitive surface to receive the projectedimage and including an endless belt supporting said photosensitivesurface; a movable frame for tensioning and aligning said endless belt;

means for driving said endless belt and including a clutch; said endlessbelt including means for indicating exposure frames; means for detectingsaid exposure frames; means for supplying transfer sheets; means forcontacting individual ones of said transfer sheets with saidphotosensitive surface; means for developing and fixing the image onsaid transfer sheets; and means responsive to said detecting means forcontrolling said clutch to position said photosensitive surface toreceive said image and including a circuit for controlling said meansfor driving and said means for supplying transfer sheets. 5. Anelectrophotographic copying machine, comprising:

an exposure station for supporting an original document to be exposed; wan optical system for projecting a mirror image of said originaldocument; means for conveying a photosensitive surface to receive theprojected image, and including an endless belt having a conductive filmthereon and supporting said photosensitive surface, said photosensitivesurface comprising a thin evaporated film of noncrystalloid seleniumformed on at least a portion of said conductive film, and an organicsemiconductor film deposited on said evaporated film; means for drivingsaid endless belt; a movable frame for tensioning and aligning saidendless belt; said endless belt including means for indicating exposureframes; means for detecting said exposure frames; means responsive tosaid detecting means for controlling said driving means to position saidphotosensitive surface to receive said image; means for supplyingtransfer sheets, said transfer sheets each comprise a conductive basemember and a thin dielectric film coated on said conductive base member;means for contacting individual ones of said transfer sheets with saidphotosensitive surface and including a conductive roller engaging saidconductive base member; and means for developing and fixing the image onsaid transfer sheets. 6. An electrophotographic copying machine,comprising:

an exposure station for supporting an original document to be exposed;an optical system for projecting a. mirror image of said originaldocument and including a flash device for illuminating said originaldocument;

means for conveying a photosensitive surface to receive the projectedimage, and including an endless belt having a conductive film thereonand supporting said photosensitive surface, said photosensitive surfacecomprising a thin evaporated film of noncrystalloid selenium formed onat least a portion of said conductive film, and an organic semiconductorfilm deposited on said evaporated film;

means for driving said endless belt;

a movable frame for tensioning and aligning said endless belt;

said endless belt including means for indicating exposure frames;

means for detecting said exposure frames;

means responsive to said detecting means for actuating said flashdevice;

means for supplying transfer sheets;

means for contacting individual ones of said transfer sheets with saidphotosensitive surface; and means for developing and fixing the image onsaid transfer sheets.

7. An electrophotographic copying machine as in claim 6 wherein saidmovable frame is detachably mounted to the copying machine and includesa driving roller for moving said endless belt, a movable framesupporting said driving roller and supported on a shaft extending alongthe longitudinal axis of said endless belt, and means for extending saidmovable frame to claim 6 wherein said thin evaporated film is aseleniumtellurium alloy.

11. An electrophotographic copying machine as in claim 6 wherein saidtransfer sheets each comprise a conductive base member and a thindielectric film coated on said conductive base member and said means forcontacting includes a conductive roller engaging said conductive basemember.

2. An electrophotographic copying machine as in claim 1 wherein saidthin evaporated film is a selenium-tellurium alloy.
 3. Anelectrophotographic copying machine, comprising: an exposure station forsupporting an original document to be exposed; an optical system forprojecting a mirror image of said original document; means for conveyinga photosensitive surface to receive the projected image and including anendless belt supporting said photosensitive surface; means for drivingsaid endless belt; frame means for maintaining the longitudinalalignment of said endless belt while being driven including a movableframe supported on a shaft extending along the longitudinal axis of saidendless belt, said movable frame including a pair of said frames betweenwhich an idling roller is rotatably mounted and over which said endlessbelt travels, said side frames each having a protrusion extendingoutwardly of said idling roller so that should said endless belt shifttoward either of said side frames, the edges of said belt will come intocontact with one of said protrusions thereby causing said movable frameto rotate about said shaft to realign said belt; said endless beltincluding means for indicating exposure frames; means for detecting saidexposure frames; means responsive to said detecting means forcontrolling said driving means to position said photosensitive surfaceto receive said image; means for supplying transfer sheets; means forcontacting individual ones of said transfer sheets with saidphotosensitive surface; and means for developing and fixing the image onsaid transfer sheets.
 4. An electrophotographic copying machine,comprising: an exposure station for supporting an original document tobe exposed; an optical system for projecting a mirror image of saidoriginal document; means for conveying a photosensitive surface toreceive the projected image and including an endless belt supportingsaid photosensitive surface; a movable frame for tensioning and aligningsaid endless belt; means for driving said endless belt and including aclutch; said endless belt including means for indicating exposureframes; means for detecting said exposure frames; means for supplyingtransfer sheets; means for contacting individual ones of said transferSheets with said photosensitive surface; means for developing and fixingthe image on said transfer sheets; and means responsive to saiddetecting means for controlling said clutch to position saidphotosensitive surface to receive said image and including a circuit forcontrolling said means for driving and said means for supplying transfersheets.
 5. An electrophotographic copying machine, comprising: anexposure station for supporting an original document to be exposed; anoptical system for projecting a mirror image of said original document;means for conveying a photosensitive surface to receive the projectedimage, and including an endless belt having a conductive film thereonand supporting said photosensitive surface, said photosensitive surfacecomprising a thin evaporated film of non-crystalloid selenium formed onat least a portion of said conductive film, and an organic semiconductorfilm deposited on said evaporated film; means for driving said endlessbelt; a movable frame for tensioning and aligning said endless belt;said endless belt including means for indicating exposure frames; meansfor detecting said exposure frames; means responsive to said detectingmeans for controlling said driving means to position said photosensitivesurface to receive said image; means for supplying transfer sheets, saidtransfer sheets each comprise a conductive base member and a thindielectric film coated on said conductive base member; means forcontacting individual ones of said transfer sheets with saidphotosensitive surface and including a conductive roller engaging saidconductive base member; and means for developing and fixing the image onsaid transfer sheets.
 6. An electrophotographic copying machine,comprising: an exposure station for supporting an original document tobe exposed; an optical system for projecting a mirror image of saidoriginal document and including a flash device for illuminating saidoriginal document; means for conveying a photosensitive surface toreceive the projected image, and including an endless belt having aconductive film thereon and supporting said photosensitive surface, saidphotosensitive surface comprising a thin evaporated film ofnon-crystalloid selenium formed on at least a portion of said conductivefilm, and an organic semiconductor film deposited on said evaporatedfilm; means for driving said endless belt; a movable frame fortensioning and aligning said endless belt; said endless belt includingmeans for indicating exposure frames; means for detecting said exposureframes; means responsive to said detecting means for actuating saidflash device; means for supplying transfer sheets; means for contactingindividual ones of said transfer sheets with said photosensitivesurface; and means for developing and fixing the image on said transfersheets.
 7. An electrophotographic copying machine as in claim 6 whereinsaid movable frame is detachably mounted to the copying machine andincludes a driving roller for moving said endless belt, a movable framesupporting said driving roller and supported on a shaft extending alongthe longitudinal axis of said endless belt, and means for extending saidmovable frame to tension said endless belt.
 8. An electrophotographiccopying machine as in claim 7 wherein said movable frame furtherincludes means for engaging each side of said endless belt to rotatesaid movable frame about said shaft to re-align said endless belt.
 9. Anelectrophotographic copying machine as in claim 6 wherein said means fordriving includes a clutch and said means responsive to said detectingmeans controls said clutch and includes a circuit for controlling saidmeans for driving and said means for supplying transfer sheets.
 10. Anelectrophotographic copying machine as in claim 6 wherein said thinevaporated film is a selenium-tellurium alloy.
 11. Anelectrophotographic copyinG machine as in claim 6 wherein said transfersheets each comprise a conductive base member and a thin dielectric filmcoated on said conductive base member and said means for contactingincludes a conductive roller engaging said conductive base member.